From patchwork Tue Aug 5 01:54:56 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dheeraj Jamwal X-Patchwork-Id: 4675371 Return-Path: X-Original-To: patchwork-ltsi-dev@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 2ED839F38C for ; Tue, 5 Aug 2014 01:53:51 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 213DC20166 for ; Tue, 5 Aug 2014 01:53:50 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 388282014A for ; Tue, 5 Aug 2014 01:53:45 +0000 (UTC) Received: from mail.linux-foundation.org (localhost [IPv6:::1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 53239BD2; Tue, 5 Aug 2014 01:52:07 +0000 (UTC) X-Original-To: ltsi-dev@lists.linuxfoundation.org Delivered-To: ltsi-dev@mail.linuxfoundation.org Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 3BF22BD7 for ; Tue, 5 Aug 2014 01:52:05 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id A45C82020B for ; Tue, 5 Aug 2014 01:52:04 +0000 (UTC) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP; 04 Aug 2014 18:52:04 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.01,802,1400050800"; d="scan'208";a="583424914" Received: from ubuntu-desktop.png.intel.com ([10.221.122.132]) by orsmga002.jf.intel.com with ESMTP; 04 Aug 2014 18:52:03 -0700 From: Dheeraj Jamwal To: ltsi-dev@lists.linuxfoundation.org Date: Tue, 5 Aug 2014 09:54:56 +0800 Message-Id: <1407203723-24877-15-git-send-email-dheerajx.s.jamwal@intel.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1407203723-24877-1-git-send-email-dheerajx.s.jamwal@intel.com> References: <1407203723-24877-1-git-send-email-dheerajx.s.jamwal@intel.com> X-Spam-Status: No, score=-4.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org Subject: [LTSI-dev] [PATCH 14/41] drm/i915: Use a spin lock to protect the pipe crc struct X-BeenThere: ltsi-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: "A list to discuss patches, development, and other things related to the LTSI project" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: ltsi-dev-bounces@lists.linuxfoundation.org Errors-To: ltsi-dev-bounces@lists.linuxfoundation.org X-Virus-Scanned: ClamAV using ClamSMTP From: Damien Lespiau Daniel pointed out that it was hard to get anything lockless to work correctly, so don't even try for this non critical piece of code and just use a spin lock. v2: Make intel_pipe_crc->opened a bool v3: Use assert_spin_locked() instead of a comment (Daniel Vetter) v4: Use spin_lock_irq() in the debugfs functions (they can only be called from process context), Use spin_lock() in the pipe_crc_update() function that can only be called from an interrupt handler, Use wait_event_interruptible_lock_irq() when waiting for data in the cicular buffer to ensure proper locking around the condition we are waiting for. (Daniel Vetter) Suggested-by: Daniel Vetter Signed-off-by: Damien Lespiau Signed-off-by: Daniel Vetter (cherry picked from commit d538bbdfde34028b5c5b0ba92b3c2096c5afb82c) Signed-off-by: Dheeraj Jamwal --- drivers/gpu/drm/i915/i915_debugfs.c | 66 ++++++++++++++++++++++++----------- drivers/gpu/drm/i915/i915_drv.h | 5 +-- drivers/gpu/drm/i915/i915_irq.c | 12 +++++-- 3 files changed, 58 insertions(+), 25 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 25fc384..5c45e9e 100644 --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -1772,13 +1772,18 @@ static int i915_pipe_crc_open(struct inode *inode, struct file *filep) struct drm_i915_private *dev_priv = info->dev->dev_private; struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[info->pipe]; - if (!atomic_dec_and_test(&pipe_crc->available)) { - atomic_inc(&pipe_crc->available); + spin_lock_irq(&pipe_crc->lock); + + if (pipe_crc->opened) { + spin_unlock_irq(&pipe_crc->lock); return -EBUSY; /* already open */ } + pipe_crc->opened = true; filep->private_data = inode->i_private; + spin_unlock_irq(&pipe_crc->lock); + return 0; } @@ -1788,7 +1793,9 @@ static int i915_pipe_crc_release(struct inode *inode, struct file *filep) struct drm_i915_private *dev_priv = info->dev->dev_private; struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[info->pipe]; - atomic_inc(&pipe_crc->available); /* release the device */ + spin_lock_irq(&pipe_crc->lock); + pipe_crc->opened = false; + spin_unlock_irq(&pipe_crc->lock); return 0; } @@ -1800,12 +1807,9 @@ static int i915_pipe_crc_release(struct inode *inode, struct file *filep) static int pipe_crc_data_count(struct intel_pipe_crc *pipe_crc) { - int head, tail; - - head = atomic_read(&pipe_crc->head); - tail = atomic_read(&pipe_crc->tail); - - return CIRC_CNT(head, tail, INTEL_PIPE_CRC_ENTRIES_NR); + assert_spin_locked(&pipe_crc->lock); + return CIRC_CNT(pipe_crc->head, pipe_crc->tail, + INTEL_PIPE_CRC_ENTRIES_NR); } static ssize_t @@ -1831,20 +1835,30 @@ i915_pipe_crc_read(struct file *filep, char __user *user_buf, size_t count, return 0; /* nothing to read */ + spin_lock_irq(&pipe_crc->lock); while (pipe_crc_data_count(pipe_crc) == 0) { - if (filep->f_flags & O_NONBLOCK) + int ret; + + if (filep->f_flags & O_NONBLOCK) { + spin_unlock_irq(&pipe_crc->lock); return -EAGAIN; + } - if (wait_event_interruptible(pipe_crc->wq, - pipe_crc_data_count(pipe_crc))) - return -ERESTARTSYS; + ret = wait_event_interruptible_lock_irq(pipe_crc->wq, + pipe_crc_data_count(pipe_crc), pipe_crc->lock); + if (ret) { + spin_unlock_irq(&pipe_crc->lock); + return ret; + } } /* We now have one or more entries to read */ - head = atomic_read(&pipe_crc->head); - tail = atomic_read(&pipe_crc->tail); + head = pipe_crc->head; + tail = pipe_crc->tail; n_entries = min((size_t)CIRC_CNT(head, tail, INTEL_PIPE_CRC_ENTRIES_NR), count / PIPE_CRC_LINE_LEN); + spin_unlock_irq(&pipe_crc->lock); + bytes_read = 0; n = 0; do { @@ -1864,10 +1878,13 @@ i915_pipe_crc_read(struct file *filep, char __user *user_buf, size_t count, BUILD_BUG_ON_NOT_POWER_OF_2(INTEL_PIPE_CRC_ENTRIES_NR); tail = (tail + 1) & (INTEL_PIPE_CRC_ENTRIES_NR - 1); - atomic_set(&pipe_crc->tail, tail); n++; } while (--n_entries); + spin_lock_irq(&pipe_crc->lock); + pipe_crc->tail = tail; + spin_unlock_irq(&pipe_crc->lock); + return bytes_read; } @@ -2111,8 +2128,10 @@ static int pipe_crc_set_source(struct drm_device *dev, enum pipe pipe, if (!pipe_crc->entries) return -ENOMEM; - atomic_set(&pipe_crc->head, 0); - atomic_set(&pipe_crc->tail, 0); + spin_lock_irq(&pipe_crc->lock); + pipe_crc->head = 0; + pipe_crc->tail = 0; + spin_unlock_irq(&pipe_crc->lock); } pipe_crc->source = source; @@ -2122,13 +2141,19 @@ static int pipe_crc_set_source(struct drm_device *dev, enum pipe pipe, /* real source -> none transition */ if (source == INTEL_PIPE_CRC_SOURCE_NONE) { + struct intel_pipe_crc_entry *entries; + DRM_DEBUG_DRIVER("stopping CRCs for pipe %c\n", pipe_name(pipe)); intel_wait_for_vblank(dev, pipe); - kfree(pipe_crc->entries); + spin_lock_irq(&pipe_crc->lock); + entries = pipe_crc->entries; pipe_crc->entries = NULL; + spin_unlock_irq(&pipe_crc->lock); + + kfree(entries); } return 0; @@ -2823,7 +2848,8 @@ void intel_display_crc_init(struct drm_device *dev) for (i = 0; i < INTEL_INFO(dev)->num_pipes; i++) { struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[i]; - atomic_set(&pipe_crc->available, 1); + pipe_crc->opened = false; + spin_lock_init(&pipe_crc->lock); init_waitqueue_head(&pipe_crc->wq); } } diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 48cbea1..7ec2a4a 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -1251,10 +1251,11 @@ struct intel_pipe_crc_entry { #define INTEL_PIPE_CRC_ENTRIES_NR 128 struct intel_pipe_crc { - atomic_t available; /* exclusive access to the device */ + spinlock_t lock; + bool opened; /* exclusive access to the result file */ struct intel_pipe_crc_entry *entries; enum intel_pipe_crc_source source; - atomic_t head, tail; + int head, tail; wait_queue_head_t wq; }; diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 8f7baad..1a7dc77 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -1200,15 +1200,19 @@ static void display_pipe_crc_irq_handler(struct drm_device *dev, enum pipe pipe, struct intel_pipe_crc_entry *entry; int head, tail; + spin_lock(&pipe_crc->lock); + if (!pipe_crc->entries) { + spin_unlock(&pipe_crc->lock); DRM_ERROR("spurious interrupt\n"); return; } - head = atomic_read(&pipe_crc->head); - tail = atomic_read(&pipe_crc->tail); + head = pipe_crc->head; + tail = pipe_crc->tail; if (CIRC_SPACE(head, tail, INTEL_PIPE_CRC_ENTRIES_NR) < 1) { + spin_unlock(&pipe_crc->lock); DRM_ERROR("CRC buffer overflowing\n"); return; } @@ -1223,7 +1227,9 @@ static void display_pipe_crc_irq_handler(struct drm_device *dev, enum pipe pipe, entry->crc[4] = crc4; head = (head + 1) & (INTEL_PIPE_CRC_ENTRIES_NR - 1); - atomic_set(&pipe_crc->head, head); + pipe_crc->head = head; + + spin_unlock(&pipe_crc->lock); wake_up_interruptible(&pipe_crc->wq); }